<?php
//1. Find SESSION:
session_start();
//2. Delete all variables in session:
$_SESSION=array();
//3. Delete all cookies:
if(isset($_COOKIE[session_name()]))
    setcookie(session_name(),time()-3600,'/',0,0);
//4. Delete Session:
    session_destroy();

//5. Direct to login.php
    header('Location: login.php?start=1');
?>